Theoretical study of CO2 hydrogenation to methanol on isolated small Pdx clusters

CO2 hydrogenation to methanol on small size Pdxclusters(x = 7, 9 and 13) has been studied using density functional theory calculations. It has been found that in contrast to metallic Pd system, these small Pdxclusters can interact well with CO2 molecule. CO2 molecule can be adsorbed with a bidendate configuration on the Pdxclusters. The formation of CO2 bidendate adsorption configuration facilitates the first step of CO2 hydrogenation reaction on the clusters. The energy profiles for formate pathway and reverse water gas shift + CO hydrogenation pathways on Pdxclusters are quite similar with Cu(111) surface, except for the first and last hydrogenation steps where the Pdxclusters have lower activation energies. This improvement causing the Pdxclusters to have a tolerable turn over frequencies values. In general, the usage of Pd in the form of small size cluster can improve the catalytic performance of metallic Pd for the CO2 hydrogenation to methanol because small size Pd cluster can act not only as an H2 dissociation center but also as a CO2 hydrogenation center.

Multimodal label-free microscopy

This paper reviews the different multimodal applications based on a large ext ent of label-freeinaging modalities,ranging from linear to nonlinear optics,while also inchuding spectroscopicmeasurements.We put specific emphasis on multimodal measurements going across the usual boundaries between imaging modalities,whereas most multimodal platforms combine techniquesbased on similar light interactions or similar hardware implementations.In this review,we limitthe scope to focus on applications for biology such as live cells or tissues,since by their nat ure ofbeing alive or fragile,we are often not free to take liberties with the image acquisition times andare forced to gather the maximum amount of information possible at one time.For such samples,imaging by a given label-free method usually presents a challenge in obt aining suficient opticalsignal or is limited in terms of the types of observable targets.Multimodal imaging is thenparticularly attractive for these samples in order to maximize the amount of measured infor-mation.While multimodal imaging is always useful in the sense of acquiring additional infor-mation from additional modes,at times it is possible to attain information that could not bediscovered using any single mode alone,which is the essence of the progress that is possible usinga multimodal approach.

Development of composite functional tissue sheets using hiPSC-CMs and hADSCs to improve the cardiac function after myocardial infarction

Human-induced pluripotent stem cell-derived cardiomyocytes(hiPSC-CMs)have been widely used in therapy of ischemic heart disease.However,there are still remaining issues that limit the therapeutic efficacy,such as immune rejection and low retention of hiPSC-CMs.Human adipose mesenchymal stromal cells(hADSCs)have been reported to be able to regulate the immune response,promote angiogenesis and promote the maturation of hiPSC-CMs.In this study,we co-cultured these two types of cells on fiber scaffold made of biodegradable poly(D,L-lactic-co-glycolic acid)(PLGA)polymer for several days to develop a composited 3D cardiac tissue sheet.As expected,the cells formed 231.00±15.14μm thickness tissue,with improved organization,alignment,ECM condition,contractile ability,and paracrine function compared to culture hiPSC-CMs only on PLGA fiber.Furthermore,the composited 3D cardiac tissue sheet significantly promoted the engraftment and survival after transplantation.The composited 3D cardiac tissue sheet also increased cardiac function,attenuated ventricular remodeling,decreased fibrosis,and enhanced angiogenesis in rat myocardial infarction model,indicating that this strategy wound be a promising therapeutic option in the clinical scenario.

Mechanocatalysis of CO to CO_(2)on TiO_(2)surface controlled at atomic scale

The common ways to activate a chemical reaction are by heat,electric current,or light.However,mechanochemistry,where the chemical reaction is activated by applied mechanical force,is less common and only poorly understood at the atomic scale.Here we report a tip-induced activation of chemical reaction of carbon monoxide to dioxide on oxidized rutile TiO_(2)(110)surface.The activation is studied by atomic force microscopy,Kelvin probe force microscopy under ultrahigh-vacuum and liquid nitrogen temperature conditions,and density functional theory(DFT)modeling.The reaction is inferred from hysteretic behavior of frequency shift signal further supported by vector force mapping of vertical and lateral forces needed to trigger the chemical reaction with torque motion of carbon monoxide towards an oxygen adatom.The reaction is found to proceed stochastically at very small tip-sample distances.Furthermore,the local contact potential difference reveals the atomic-scale charge redistribution in the reactants required to unlock the reaction.Our results open up new insights into the mechanochemistry on metal oxide surfaces at the atomic scale.

Silver hierarchical structures grown on microstructured silicon in chip for microfluidic integrated catalyst and SERS detector

In this Letter, silver（Ag） hierarchical nanostructures grown on black silicon（BS） are used as the catalyst and a surface-enhanced Raman scattering（SERS） detector integrated in a microfluid. The BS is fabricated via femtosecond laser ablation in an atmosphere of sulfur hexafluoride, and then hydrogenated with hydrofluoric acid. As formed, the BS substrate directly acts as a reducing template to grow silver hierarchical nano-structures.Particularly, Ag-BS composite micro/nano-structures can be in-situ constructed in silicon-based microchannels.These structures simultaneously serve as integrated catalytic reactors and a SERS substrate for sensing. The sensitivity is tested to be as low as 10-8mol∕L using Rhodamine 6G.

Single-Walled Carbon Nanotube Growth with Non-Iron- Group “Catalysts” by Chemical Vapor Deposition

Various materials have been found to“catalyze”carbon nanotube growth in chemical vapor deposition(CVD)when they become nano-sized particles.These involve not only metals,such as Pd,Pt,Au,Ag,and Cu,but also semiconductors,such as Si,Ge,and SiC.Alumina and diamond nanoparticles also produce carbon nanotubes.These“catalysts”,which are better called“seeds”,can be categorized into two types:one type forms a eutectic liquid or highly-mobile alloy with carbon,and carbon atoms precipitate from the eutectic alloy;the other type remains as a solid phase and form a carbon surface layer during CVD growth.In this paper,we review recent studies of SWCNT growth with these non-iron-group materials and highlight the mechanisms involved.

Probing CO on a rutile TiO_(2)(110)surface using atomic force microscopy and Kelvin probe force microscopy

Probing CO at a specific site on a metal oxide surface is essential for characterizing various applications such as CO oxidation,hydrogenation,and water–gas shift reaction.Herein,we use atomic force microscopy and Kelvin probe force microscopy to probe the CO on a rutile TiO_(2)(110)surface.Our results indicate that CO can be manipulated along the Ti row by the repulsive lateral force of“pushing”mode.Furthermore,the joint combination of precise manipulation and the distance dependence of local contact potential difference allow us to resolve the interatomic dipole moment and charge state of CO at atomic resolution.Therefore,we found that the negatively charged CO with the dipole moment of negative pole down on the rutile TiO_(2)(110)surface.Our results suppose that both the charge state as well as the on-surface dipole interaction are very effective for CO reaction on rutile TiO_(2)(110)surface.

Gold nanostructure based LSPR biosensors

The localized surface plasmon resonance (LSPR) of noble metal nanoparticles have been described in numerous articles. Changes in the peak intensity and wavelength of

Coaxial boron nitride nanotubes as interfacial dielectric layers to lower interface trap density in carbon nanotube transistors

A semiconductor/dielectric interface is one of the dominant factors in device characteristics,and a variety of oxides with high dielectric constants and low interface trap densities have been used in carbon nanotube transistors.Given the crystal structure of nanotubes with no dangling bonds,there remains room to investigate unconventional dielectric materials.Here,we fabricate carbon nanotube transistors with boron nitride nanotubes as interfacial layers between channels and gate dielectrics,where a single semiconducting nanotube is used to focus on switching behaviors at the subthreshold regime.The subthreshold swing of 68 mV·dec^(−1)is obtained despite a 100-nm-thick Sio_(2)dielectric,corresponding to the effective interface trap density of 5.2×10^(11)cm^(−2)·eV^(−1),one order of magnitude lower than those of carbon nanotube devices without boron nitride passivation.The interfacial layers also result in the mild suppression of threshold voltage variation and hysteresis.We achieve Ohmic contacts through the selective etching of boron nitride nanotubes with XeF2 gas,overcoming the trade-off imposed by wrapping the inner nanotubes.Negligible impacts of fluorinating carbon nanotubes on device performances are also confirmed as long as the etching is applied exclusively at source/drain regions.Our results represent an important step toward nanoelectronics that exploit the advantage of one-dimensional van der Waals heterostructures.